Bumblebees are vital pollinators, especially in temperate areas, due to their buzz-pollinated ability. Bumblebees can be found in the tropical of Southeast Asia, mainly in the highlands. There are 23 species in 7 subgenera, recorded in Southeast Asia. Only three subgenera Megabombus, Melanobombus, and Pyrobombus, have been reported both in the mainland and archipelago. Studying the biogeography of Southeast Asian bumblebees might reveal the tropical adaptation process and distribution pattern which are vital for the conservation plan. However, the genetic relationship between mainland and island species for performing biogeographic analysis is still incomplete. In this study, we chose B. (Pyrobombus) flavescens Smith as a model for biogeographic reconstruction because this species is the most widespread bumblebee species in Southeast Asia. The biogeographic scenarios were estimated from a Bayesian phylogenetic analysis of B. flavescens populations across the current range, combining COI, 16S, and PEPCK data, using S-DIVA analysis in RASP and BioGeoBEARS with DIVALIKE+J analysis. The result suggested that B. flavescens diverged from its sister lineage in the Himalayas and dispersed into Southeast Asia in the Pleistocene. Then, the oscillation of sea level and rising of global temperature in the late Pleistocene facilitated the allopatric divergence process of B. flavescens, including population isolation and higher latitude immigration, for example, the Cameron Highlands in Malaysia. For the next step, a species distribution model with paleoclimatic data, including temperature and humidity, would be a promising tool to illustrate the biogeographic scenarios of B. flavescens comprehensively.
Keywords DNA barcoding, Museum specimens, Polymorphism, Philippines, Taxonomic impediment